Muffler



Feb. 19, 1935. c. M, JOHNSON MUFFLER Filed May 5, 1952 ATTORN EYSPatented Feb. 19, 1935 UNITED STATES .PATENT loFFlcla.

6 Claims.

This invention relates in general to silencers and more particularly tosilencers for internal combustion engines.

An object of the invention is to provide a silencer which will be ofsimple and durable construction, easy and inexpensive to make andassemble.

Another object is to provide a silencer which allows for a continuousbut retarded iiow of exhaust gases and to provide an induction systemwhich will insure a helical airflow without the necessity of impedinghelical louvers which would tend to build up prejudicial back pressurein the engine to which the silencer may be connected.

It is a further object to provide a silencer wherein there will alwaysbe a direct air passage to the discharge end and wherein a series ofrelatively small louvers not suicient to build up any appreciable backpressure will constitute an induction system which will not structurallylimit the flow of gases, but which will cause the flow to follow ahelical path.

It is a still further object to provide a silencer that will eiectivelybreak down the frequency which may set up by the explosions of theengine 25' so as to silence the effect of the explosions.

With the foregoing and other objects in view, the invention consists inthe combination of parts and in the details of construction set forth inthe following specification and appended claims, certain embodimentsbeing'illustrated in the accompanying drawing, in which: 1

Figure 1 is a'view in longitudinal section through the silencer; p

Figure 2 is a section taken along line 2--2 of Figure 1. r

Referring more particularly to the drawing, the silencer consists in anouter casing l and an inner casing 2, which may be suitably secured at 3and 4 to the outer casing. The innerv casing is provided with a seriesof louvers, each of which may be formed by cutting transversely throughthe preferably malleable metal for a relatively slight distance, andhammering the casing immediately behind the cut until a louver is formedwhich projects to a degree into the casing and predetermined by the sizeof the cut and the extent of hammering. The hammering does not affectthe general overall dimensions of the casing. These louvers are formedboth in the upper and lower sides of the inner cylindrical casing andthe upper and lower louvers are arranged in staggered relation.

For instance, as shown in Figures 1 and 2, the lower side of the casinghaving been cut at 5 and the wall having been hammered down behind thecut to form a louver 9 instead of ahead of the cut,

as is the case in the upper louvers, where the casing is cut at 6 andthe wall hammered inwardly an inclined louver 7 is formed which willdeflect the gases through the opening 8 provided for in 5 the forming ofthe louver. The upper louver '7 is substantially parallel to louvers 9and 10, as is the case of all louvers and is arranged in sulcientstaggered relation to lower louver 9 so as to provide for a direct flowof gases injected through 10 the upper opening 8 from the lower opening9 through the inner casing and out through the lower opening 11 andagain into the outer casing.

As stated before, the louvers only extenda relatively short distanceinto the casing so that there 15 is a substantially uninterruptedcentral bore for free passage of the gases unobstructed by anythingwhich would cause the building up of back pressure. The gases near theinner periphery of the casing will, however, be deflected downwardly bythe front louver 9 through the outlet 9. The subsequent lower louvers14, 16 and 18 likewise dellect such peripheralgasesv through thecorresponding openings 14', 16 and 18. The upper louvers are inclined inthe opposite direction so that upperlouver 7 in forcing the gasesdownwardly give them an impetus in the direction of the lower openingl1. Furthermore, an induction effect is obtained in that the gases ofthe inner casing, in being deflected downwardly by louver 7, create asuction at the upper opening 8, causing the gases which have beendeflected by the lower louver 9 into the outer casing through the loweropening 9. to be drawn in through the upper opening 8. The path taken bythe gases under such induction is helical, even though there is noimpeding spiral louver. The staggered relation of the simple inwardlyextending upper and lower louvers brings about the induction andtortuous or helical ow of the gases.

The formation and disposition of the lower louvers is such as to providean eilicient deflector, without impeding the gas flow sufficient tobuild up any appreciable prejudicious back pressure. The same formationbut reverse disposition of the upper louvers provides for severalnecessary advantageous results. First they allow for a centralsubstantially uninterrupted flow, and sec- `ondly they are so disposedas to deflect the peripheral gases in a direction toward the lowercorresponding outlet. A further feature is that the upper curved surfaceof each upper louver simulates the curvature of an aerofoil which makesfor an acceleration of ow as the gases ow toward the rear end. As thisacceleration.

builds up, so does the induction ofthe gases from the preceding lowerlouvers. The upper and lower louvers are so arranged in such staggeredrelation that not only are the gases of the inner casing deflected bythe upper louvers toward the lower 'openings aided by the lower louvers,but the upper louvers also cause the inducted gases to be directedtoward the lower openings whence they are additionally guided by thelower louvers.`

'Ihis lconstruction provides,ior an effective silencing with the minimumretardation of the discharge of the gases. There is always a direct'substantially uninterrupted iiow of the centrally disposed gases. 'I'hehelical tlow oi the peripheral gases is accelerated in nature and beingbrought about inherently rather than strictly structural does notproduce disadvantageous back .pressure but merely provides a steadyhelical now which eiiiciently destroys sound frequencies which wouldotherwise be set up by the intermittent explosions and the consequentcentral galiiow.

In carrying out the above principles, I further progressively diminishthe impeding ei'iect on the gases from the inlet toward the outlet endoi the silencer. To bring this about, I in reality increase the size ofthe upper louvers and the corresponding upper apertures, the size o! thelower louvers and apertures remaining uniform, and I also increase thedistance between the upper louvers and between the lower louvers aswell, with the diameter of the inner casing remaining uniformthroughout. The increased spacing between 'the louvers brings about alonger helix of iiow or, in other words, has a tendency to straightenout the tortuous or helical iiow. The increase in the size of the upperlouvers and apertures compensates for the increase in space between thelouvers and is found to be desirous in obtaining eilicient induction tomaintain the helical ilow throughout and the blending o! the gases insuch a manner as to break down any frequency which may be set up byengine explosions.

I claim' l. A silencer comprising an inner and an outer casing, saidinner casing being open at its inlet and discharge ends and providedwith a sub.- stantially uninterrupted central passageway, a plurality ofrows of louvers with adjacent apertures arranged in substantially theopposite walls o! said inner casing. the louvers of one oi said rowsextending diagonally toward the discharge end with adjacent aperturesarranged toward said end,4 the louvers of the other of said rowsextending toward the inlet end with adjacent apertures arranged towardsaid end.

2. A silencer comprising an inner and an outer casing, said inner casingbeing open at its inlet and discharge ends and provided with asubstantially uninterrupted central eway, a plurality of rows of louverswith adjacent apertures arranged in substantially the opposite walls ofsaid inner casing, the louvers oi.' one of said rows extendingdiagonally toward the discharge end with adjacent apertures arrangedtoward said end, the louvers of the other oi said rows extending towardthe inlet end with adjacent apertures arranged toward said end, thedepth of the louvers o! both of said rows and adjacent apertures beingprogressively increased toward said discharge end.

3. A silencer for iluids comprising an inner and an outer casing. saidinner casing being open at its inlet and discharge ends, means forinducing a substantially helical now oi said iluids through said outercasing and transversely through said inner casing, said means includinga plurality oi rows oflouvers and apertures in substantially theopposite walls of said inner casing, each ot the louvers of one rowextending inwardly from the wall of said inner casing and behind anadjacent aperture and each of the louvers ot the other row extendinginwardly from the wall of said inner casing in advance oi' an adjacentaperture, the louvers of one row extending in an opposite direction tothe louvers of the other row.

4. A silencer for uids comprising an inner and an outer casing, saidinner casing being open at its inlet and discharge ends, means forinducing a substantially helical ilow oi said iiuids through said outercasing and transversely through said inner casing, said means includinga plurality oi rows of louvers and apertures in substantially theopposite walls of said inner casing, each of the louvers of one rowextending inwardLv from the wail oi said inner casing and behind anadjacent aperture and each of the louvers of the other row extendinginwardly from the wall of said inner casing in advance of an adjacentaperture, the louvers and apertures of one row being staggered withrespect to those of the other row.

5. A silencer for uids comprising aninner and an outer casing, saidinner casing being open at its inlet and discharge ends, means forinducing a substantially helical flow of said iiuids through said outercasing and transversely through said inner casing, said means includinga plurality of rows oi! louvers and apertures in substantially theopposite walls o! said inner casing, each ot the louvers of one rowextending inwardly from the wall of said inner casing and behind anadjacent aperture and each of the louvers of the other row extendinginwardly from the wall oi said inner casing in advance of an adjacentaperture, the louvers oi one row being staggered with respect to thoseo! the other row,

said louvers being struck out oi the walls of said inner casing andarranged to extend diagonally with respect thereto. l

6. A silencer comprising an inner and outer casing, said inner casingbeing open at its inlet and discharge ends and provided with asubstantially uninterrupted central passageway, a plurality of opposedrows of louvers with adjacent apertures arranged in substantially theopposite walls of said inner casing, the louvers of one of said rowsextending diagonally inwardly toward the discharge end with adjacentapertures arranged towards said end, the louvers of the other o! saidrows extending toward the inlet end with adjacent apertures arrangedtoward said end.

CORYDON M. JOHNSON.

